Patent GB-651759-A (GB)
Title: Photographic cameras
IPC: G03B9/46
Filed: 1948-04-16
Abstract: 651,759. Photographic cameras. PETERSEN, C. April 16, 1948, No. 10618. [A Specification was laid open to inspection under Sect. 91 of the Acts, Oct. 19, 1948.] [Class 98 (i)] A photographic camera comprises a lens 4 which is received in the front wall 13 of the camera body and is aligned with an aperture 3 in the rear wall 2. The light-sensitive film overlies this aperture 3 and between the aperture and lens is a hood 46 preventing stray light from reaching the film and a shutter comprising two screens 5, 6. Each screen consists of two sector-shaped plates 7, 71 and 8, 81 joined by an integral web 51 and 61. The curved edges of screen 5 each carry at the ends thereof remote from web 5<SP>1</SP> a spring blade 9 and the curved edges of screen 6 each carry at the ends thereof adjacent web 61 a spring blade 10. Each blade is secured at its other end to the front wall 13 of the camera body as at 47 for one blade 9. The web 61 of screen 6 carries a pin 15 which, during the setting of the shutter, contacts a pivoted lever 25 and rotates it anti-clockwise. The upper edges of the webs 51, 61 are in contact during setting of the shutter and, when the set position is reached, a stepped surface 17 on a trip lever 16 falls behind pin 15 and thus prevents premature return movement of the screens and lever 25. The latter has a curved surface 24 on which a lever 22 is held frictionally by a spring blade 23. Thus lever 22 moves with lever 25 until it contacts a prong 36 on an arm 35 carried by a sleeve 38 which is manually operable by a knob 37 and is rotatable and slidable against the action of a spring 39 on the shaft carrying lever 25. The position of arm 35 determines the position of lever 22 relative to lever 25 which, in turn, determines the exposure time. If further movement of lever 22 is necessary, knob 37 is depressed so that arm 35 moves along the shaft carrying lever 25 and the lever 22 is gripped between the prong 36 and a further prong 40 on the arm 35 ; knob 37 is now rotated to the desired extent and the lever 22 is moved to the position corresponding to the desired exposure time. On releasing knob 37, sleeve 38 and arm 35 slide under the action of spring 39 so that a pin 41 projecting from sleeve 38 engages one of the slots 43 in a collar 42 and thus prevents further rotation of arm 35. The shutter is released by movement of a projection 20 from trip lever 16 ; this movement causes lever 16 to rotate anti-clockwise about a pivot 19 and release pin 15 from the stepped surface 17 on the lever. Screen 6 then rolls on front wall 15 under the action of the spring blades 10, and the levers 25, 22 are rotated clockwise by a spring 26 attached to the lever 25 and the camera body. After a time interval determined by the position of lever 22 on surface 24, the end of this lever contacts a projection 21 on a lever, which is pivoted to the lever 16 at 30 and which has a stepped surface 18 that engages a pin 14 on one plate 7 of screen 5 as soon as screen 6 is released, and releases the catch 18 so that screen 5 now rolls on the front wall 13 under the action of spring blades 9 until the upper edges of webs 5<SP>1</SP>, 61 again come into contact to close the shutter.